Black Friday is the day where companys will get in the "black" instead of the "red" for the year. It is the day after Thanksgiving and companys have tons of sells. Coach outlets apparently have sales but the boutiques do not. It is only on that Friday but stores usually continue to have sells until New Years.
It is when all the insane people go shopping, of course. Actually it is when stores that have been losing money all year (in the red) make enough money to be making a profit (in the black). It is always the day after Thanksgiving here in the States. Most major stores have big door buster sales where they have limited supplies of something they think everyone will want for ridiculous low prices. If they get enough people in the store, people will buy stuff even if they aren't getting one of the door buster items.